Regenerator and heater arrangement in a hot gas engine



w. F. SCHALKWIJK ET AL 6,7 7 REQENERATOR AND HEATER ARRANGEMENT IN A HOT GAS ENGINE Filed Dec. 50, 1954 Oct. 21, 1958 INVENTORS WILLEM FREDERIK SCHALKWIJK LEENDERT DE LA G AGENT U ited States Patent REGENERATOR AND HEATER ARRANGEMENT IN A HOT GAS ENGINE Willem Frederik Schalkwijk and Leendert de Lange, Emmasingel, Eindhoven, Netherlands, assignors, by mesne assignments, to North American Philips Company, Inc., New York, N. Y., a corporation of Delaware Application December 30, 1954, Serial No. 478,695 Claims priority, application Netherlands January 13, 1954 2 Claims. (Cl. 62-6) This invention relates to hot-gas reciprocating apparatus in which a space is available between the regenerator and the heat-exchanger communicating therewith. The term hot-gas reciprocating apparatus is to be understood in this case to mean a hot-gas reciprocating motor, a refrigerator and a heat pump, the two last-mentioned operating on the reversed hot-gas motor principle. As is well-known, a gas of invariable chemical composition in such apparatus is subject to a closed thermodynamic cycle, the gas remaining in the .same state of aggregation. The apparatus comprises at least two spaces, the volumes of which are varied by piston-like bodies. The spaces freely communicate with one another by way of a heater, a regenerator and a cooler. The gas is substantially expanded in one space and substantially compressed in another space.

It is known that the size of the clearance space in such apparatus influences the output or the refrigerating capacity in the case of refrigerators. As a rule, a decreased clearance space results in an increased specific power and, conversely, an increased clearance space results in a decreased specific power. However, a clearance space cannot be avoided in such apparatus, since it is always necessary to bridge a certain distance between the spaces of which the volumes are varied.

Consequently, it would be possible to aim at a structure in which the channels required for bridging are occupied as far as possible by the heater, the regenerator and the cooler. The clearance space thus is maintained, but is at least utilized. On the ground of this consideration, it would be possible to make the heater and the cooler adjoin the regenerator directly without any clearance, so that the occurrence of clearance space which is not utilized is avoided as far as possible.

It is surprisingly found that it is on the contrary undesirable for the heater and the cooler to adjoin directly the regenerator, since in this case the loss due to flow in the regenerator increases to such an extent that not only the improvement in output resulting from the smaller clearance space is fully neutralized, but even the output is decreased. In view thereof a space is required between the regenerator and a heat-exchanger, while it is found that the height of this space is required to exceed a certain minimum value.

However, it is also found that the height of the space between the regenerator and a heat-exchanger must not be excessive, otherwise very harmful variations in temperature occur in the gas contained in this space, which variations detrimentally affect the operation of the apparatus and even more than could be expected in connection with the increased clearance space.

According to the invention, the height H of this space is at least 0.1 and at the most 0.4 n n wherein S=the cross-section of the empty regenerator space n=the number of the channels in the heat-exchanger It is naturally desirable that in the width the space should not be greater than that of the regenerator.

In order that the invention may be readily carried into eliect, it will now be described with reference to the accompanying drawing, given by way of example, in which Fig. 1 shows a cold-gas refrigerator of the displacer type.

Figs. 2 and 3 show, on an enlarged scale, a cross-sec tion of a connection between a heat-exchanger and a regenerator and a cross-section of a heat-exchanger.

The refrigerator comprises a cylinder 1, in which a displacer 2 and a piston 3 can move up and down with a substantially constant phase difference. The displacer thus influences the volume of a space 4 which freely communicates with a space 8 by way of a freezer 5, a regenerator 6 and a cooler 7. The space 4 is often termed the freezing space and the space 8 is often termed the cooled space.

The displacer is coupled by way of a drivingrod system 9 to a crank of a crank-shaft 10, the piston being coupled by way of a driving rod system 11 to cranks of the same crank-shaft 10.

The refrigerator is driven by an electric motor 12 so that the piston and the displacer are moved up and down, substantially expansion occurring in the space 4 and substantially compression occurring in the space 8. The gas to be cooled, for example air, may be led along the fins provided on the outside of the freezer 5 and be condensed thereon. The working medium used in the apparatus itself may be, for example, hydrogen.

Between the lower end surface 13 of the freezer and the upper end surface 14 of the regenerator there exists a space 15 having a height H which must satisfy the aforementioned requirements. The height H is thus at least GAV and at the most 0.4 n 11.

0.6 mm.and at the most 0.4 1560 W=2J1DJIIL Similarly, a space 16 exists between the upper end surface 17 of the cooler 7 and the lower end surface 18 of the regenerator. The height H of the said space, measured in the direction in which the gas flows, must also satisfy the above-mentioned requirements.

Figs. 2 and 3 show, on an enlarged scale, cross-sections of the connection between a heat-exchanger and a regenerator, Fig. 3 being a cross-section taken along the line III-III of Fig. 2. In this embodiment the heatexchanger comprises a plurality of parallel channels 19 spaced apart by fins 20. However, the invention is also applicable, if the heat-exchanger comprises pipes, or if the heat-exchanger comprises only one channel. Furthermore, it is desirable that the sectional area of the space is not smaller than that of the regenerator space.

What is claimed is:

1. A hot-gas reciprocating apparatus comprising a freezer, regenerator and cooler arranged in that sequence, said freezer and cooler having a plurality of substantially parallel channels therein, said regenerator being separated from contact with said freezer and cooler by a space "Patented Oct. 21, 1958" 2,856,757 v 3 4 betwecnsaidfreezer' andregenerator and a space between claim 1 wherein said freezer and cooler includes'a pluthela er nd said cooler, each of said spaces having a rality of spaced fins forming said plurality of substantially height H which is at least I parallel channels.

x/1% and at a maximum x/g 5 References Cited in the file of this patent h S fth t t UNITED STATES PATENTS w en e cross-sec 10m 0 e emp y regencra or space 2 011 964 I k am Aug. 20,. .1935 galley-the number of channels 1n the freezer or the 2,745,262 Kohler May 15, 1956 2. A hot gas reciprocating apparatus as claimed in 10 

